The Effects of Private Insurance on Measures of Health: Evidence from the Health and Retirement Study

In this paper we investigate whether the presence of private insurance leads to improved health status. Using the Health and Retirement study we focus on adults in late middle age who are nearing entry into Medicare. Estimation addresses endogeneity of the insurance participation decision in health outcome regressions. Two models are tested, an instrumental variables models, and a model with endogenous treatment effects due to Heckman (1978). Insurance participation and health behaviors enter with a lag to allow their effects to dissipate over time. Separate regressions were run for groupings of chronic conditions. We find that the overall impact of insurance on health tends to be significantly downwards biased if no adjustment for endogeneity is made. With corrections there is a four-fold increase in the insurance effect; yielding a 7 percent increase in the overall health measure for the uninsured. Results are consistent across IV and treatment effects models, and for all major groupings of medical conditions. Thus, the effect of private insurance on health may be larger than previously estimated. As for policy, expanding coverage to the uninsured should result in substantial health improvement. By conjecture, this is likely to reduce the need for health care when individuals retire and enter Medicare, potentially leading to savings.

Detection of high-power two-mode squeezing by sum-frequency generation

We introduce sum-frequency generation (SFG) as an effective physical two-photon detector for high power two-mode squeezed coherent states with arbitrary frequency separation, as produced by parametric oscillators well above the threshold. Using a formalism of "collective modes", we describe both two-mode squeezing and degenerate squeezing on equal footing and derive simple relations between the input degree of squeezing and the measured SFG quadrature noise. We compare the proposed SFG detection to standard homodyne measurement, and show advantages in robustness to detection inefficiency (loss of SFG photons) and acceptance bandwidth.Comment: 5 pages, 3 figure

The Economics of Religion, Jewish Survival and Jewish Attitudes Toward Competition in Torah Education

This paper examines the attitude of Jewish law to competition in light of the economist's understanding of the benefits of competition and of the beneficiaries from intervention in the competitive process. The punchline of this paper is simple. Although Judaism has used a whole host of restrictions on competition and has had its share of legislation to promote private interests, there has been one area that has generally been a consistent exception to impediments to competition -- the teaching of Torah. This exception is all the more remarkable because those who were in a position to influence the legislation often stood to benefit from such restrictions. From this stress on teaching, we show that the foundation was laid for the survival and perpetuation of Judaism.

Comparison of dynamic (brush) and static (pressure) mechanical allodynia in migraine

Allodynia has been described in migraine but has not been fully investigated for the different sensory modalities. The aim of this study was to compare the prevalence of dynamic (brush) and static (pressure) mechanical allodynia in migraine patients and to suggest a practical method of testing them in a clinical setting. Patients with International Headache Society-defined episodic migraine (EM) or with transformed migraine (TM) as defined by Silberstein and Lipton were prospectively recruited from the Jefferson Headache Center out-patient clinic. A questionnaire of migraine features and symptoms of allodynia was administered. Brush allodynia (BA) was tested by cutaneous stimulation with a gauze pad and pressure allodynia (PA) was tested using von Frey hairs (VFH). The prevalence of BA and PA in all patients and in the different subgroups was calculated and correlated with migraine features. We recruited 55 migraine patients. Twenty-five had EM and 30 had TM. BA was present in 18 (32.7%) patients and PA in 18–24 (32.7–43.6%). Allodynia to both brush and pressure was found in 13–17 (23.6–30.9%) patients. If a patient had allodynia to one modality only, it was more likely to be PA than BA. Both BA and PA were more common in patients with TM compared with those with EM [BA 46.7% vs. 16.0%; PA (differences significant for the medium and thick VFHs) 50% vs. 20% and 50% vs. 12%, respectively]. Both types of allodynia were also more common in patients with migraine with aura compared with those with migraine without aura (BA 57.1% vs. 17.6%; PA 57.1–61.9% vs. 17.6–32.7%). There was a positive correlation between allodynia score (as obtained by examination) and allodynia index (as obtained by history) for both BA and PA. The incomplete, although considerable, overlap between BA and PA suggests that allodynia to different sensory modalities is associated with sensitization of different neuronal populations. Because PA was more common than BA, it may be a more sensitive indicator of allodynia in migraine. PA can be tested clinically in a practical and systematic manner

Lower Limits on Aperture Size for an ExoEarth-Detecting Coronagraphic Mission

The yield of Earth-like planets will likely be a primary science metric for future space-based missions that will drive telescope aperture size. Maximizing the exoEarth candidate yield is therefore critical to minimizing the required aperture. Here we describe a method for exoEarth candidate yield maximization that simultaneously optimizes, for the first time, the targets chosen for observation, the number of visits to each target, the delay time between visits, and the exposure time of every observation. This code calculates both the detection time and multi-wavelength spectral characterization time required for planets. We also refine the astrophysical assumptions used as inputs to these calculations, relying on published estimates of planetary occurrence rates as well as theoretical and observational constraints on terrestrial planet sizes and classical habitable zones. Given these astrophysical assumptions, optimistic telescope and instrument assumptions, and our new completeness code that produces the highest yields to date, we suggest lower limits on the aperture size required to detect and characterize a statistically-motivated sample of exoEarths.Comment: Accepted for publication in ApJ; 38 pages, 16 Figures, 3 Table

Concept Mapping as a Mechanism for Assessing Science Teachers’ Cross-Disciplinary Field-Based Learning

Two common goals of science teacher professional development (PD) are increased content knowledge (CK) and improved readiness to teach through inquiry. However, PD assessment challenges arise when the context is structured around inquiry-based, participant-driven learning, and when the content crosses scientific disciplines. This study extended the use of concept mapping as an assessment tool for examining changes in the content knowledge of 21 high school science teachers who participated in a field-based environmental science summer institute. The scoring rubric focused on documenting concepts, links, and map organization and scope in an attempt to capture development of cross- disciplinary knowledge in ways that correspond with theories of expertise development. The analysis revealed significant gains from pre-PD to post PD maps in the sophistication of links between concepts and in the number of additional, participant-generated scientifically valid concepts. Relative to the initial maps, post PD maps also manifested more complete clustering of concepts. Findings are discussed in reference to previous studies on teachers’ learning and implications for future research using concept mapping as a means of assessing teacher PD

Photoassociation adiabatic passage of ultracold Rb atoms to form ultracold Rb_2 molecules

We theoretically explore photoassociation by Adiabatic Passage of two colliding cold ^{85}Rb atoms in an atomic trap to form an ultracold Rb_2 molecule. We consider the incoherent thermal nature of the scattering process in a trap and show that coherent manipulations of the atomic ensemble, such as adiabatic passage, are feasible if performed within the coherence time window dictated by the temperature, which is relatively long for cold atoms. We show that a sequence of ~2*10^7 pulses of moderate intensities, each lasting ~750 ns, can photoassociate a large fraction of the atomic ensemble at temperature of 100 microkelvin and density of 10^{11} atoms/cm^3. Use of multiple pulse sequences makes it possible to populate the ground vibrational state. Employing spontaneous decay from a selected excited state, one can accumulate the molecules in a narrow distribution of vibrational states in the ground electronic potential. Alternatively, by removing the created molecules from the beam path between pulse sets, one can create a low-density ensemble of molecules in their ground ro-vibrational state.Comment: RevTex, 23 pages, 9 figure

Investigation of local soil resistance on suction caissons at capacity in undrained clay under combined loading

Winkler modelling offers a flexible and computationally efficient framework for estimating suction caisson capacity. However, there is a limited understanding of the local soil resistance acting on caissons at capacity under combined six degrees-of-freedom (6DoF) loading, which is essential for accurately estimating caisson failure envelopes. Furthermore, existing simplified design models for caissons cannot assess capacity under non-planar lateral and moment loading, which is common in offshore wind applications. To address these limitations, this paper presents a comprehensive three-dimensional (3D) finite element analysis (FEA) study, which investigates the local soil resistance acting on the caisson at capacity in undrained clay under combined 6DoF loading. The paper introduces the concept of ‘soil reaction failure envelopes’ to characterise the interactions between soil reactions at capacity. Closed-form formulations are derived to approximate these soil reaction failure envelopes. An elastoplastic Winkler model is then developed, incorporating linear elastic perfectly plastic soil reactions based on these formulations. The results demonstrate that the Winkler model can provide efficient and reasonably accurate estimations of caisson capacity under combined 6DoF loading, even for irregular soil profiles that pose much uncertainty and challenges to existing macro-element models